Comparison and a possible source of disagreement between experimental and numerical results in a czochralski model

V. Haslavsky, E. Miroshnichenko, E. Kit, A. Yu Gelfgat

Research output: Contribution to journalArticlepeer-review

Abstract

Experimental and numerical observations of oscillatory instability of melt flow in a Czochralski model are compared, and a disagreement observed at small crystal dummy rotation rates is addressed. To exclude uncertainties connected with flow along the free surface, the latter is covered by a no-slip thermally insulating ring. Experiments reveal an appearance of oscillations at temperature differences smaller than the numerically predicted critical ones. At the same time, a steep increase of the oscillations amplitude is observed just beyond the computed threshold values. By increasing thedummy rotation gradually, we are able to qualitatively confirm the numerically predicted flow destabilization. A good quantitative comparison is reached only with a rather strong rotation of the crystal dummy. Focusing on thedisagreement in the non-rotating case, we argue that the experimentally observed instability is triggered by an external excitation that results from low-amplitude temperature oscillations in thermostatic baths. This argumentis supported by a numerical simulation of the parametrically excited model.

Original languageEnglish
Pages (from-to)209-234
Number of pages26
JournalFluid Dynamics and Materials Processing
Volume9
Issue number3
DOIs
StatePublished - 2013

Keywords

  • Convection
  • Czochralski growth
  • Oscillatory instability
  • Rotating flows

All Science Journal Classification (ASJC) codes

  • General Materials Science

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